Blood collecting assembly

ABSTRACT

A blood collecting assembly having a cannula, a holder for the cannula, and a valve which is useful in indicating when the venipuncture has been made by means of a blood telltale, which is easily compressed when the cannula is pierced through a resealable closure of a blood collecting container, which returns to the extended position when the cannula is withdrawn from the closure, and which prevents the flow of blood through the cannula when it has returned to its extended position.

D United States Patent 1 1 1111 3,886,930

Ryan June 3, 1975 [54] BLOOD COLLECTING ASSEMBLY 3,500,821 3/ 1970 Ogle 128/2 F 3,585,984 6/1971 Buchanan 128/2 F 1 Invent George Rya"! Waukegan, 3,734,080 5/1973 Petterson et a1. 128/2 F ASSlgl'lBCI AbPOtt Laboratories, lllC., North Chlcago 880,516 11/1970 Italy 128/2 F [22] Filed: Nov. 28, 1973 50,588 3/1949 France..... l28/DIG. 5 935,122 l/l948 France 128/DIG. 5 1 1 p 419,659 1,019,500 2/1966 United Kingdom 128/D1G. 5

Related US. Application Data OTHER PUBLICATIONS 1 1 Continuation f 1- 8 9 April 197; The Bulletin, Dow Corning Corp. Publication, Vol. 4,

abandoned, wh1ch 1s a commuatton-m-part of Ser. No 2 A r 1962 NO. 715, Jan. 5, 1970, abandoned. p

52 U.S. c1 128/2 F; 128/D1G. 5; 128/276; Primary Examiner-Kyle Howell 128/218 NV Attorney, Agent, or Firm-Joseph .1. Grass [51] Int. Cl A61b 5/14 [58] Field of Search 128/2 F, 2 R, DIG. 5, 221, [5 ABSTRACT 128/276, 218 NV A blood collecting assembly having a cannula, a holder for the cannula, and a valve which is useful in 1 References Clted indicating when the venipuncture has been made by UNITED STATES PATENTS means of a blood telltale, which is easily compressed 2 837 093 6/1958 Tash 128/218 when the cannula is Pierced through a resealable 2:847:995 8/1958 Adams.... 128/214 sure of a blood collecting container, which returns to 3,093,134 6/1963 Roeht 128/221 the extended position when the cannula is withdrawn 3,134,380 5/1964 Armao 128/221 UX from the closure, and which prevents the flow of 3,200,486 8/1965 29/422 blood through the cannula when it has returned to its 3,304,934 2 1967 Bautista... 128/2 1= extended position 3,366,103 H1968 Keller 128/2 F 3,469,572 9/1969 Nehring 128/2 F 7 Claims, 21 Drawing Figures PMS-HEB JUIi 3 1975 SHEET AfTORNEY BLOOD COLLECTING ASSEMBLY CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of application Ser. No. 138,990 filed Apr. 30, 1971, now abandoned, which is a continuation-in-part of application Ser. No. 715 filed Jan. 5, 1970, now abandoned.

BACKGROUND OF THE INVENTION l.'Field of the Invention This invention relates to the art of collecting blood.

2. Brief Description of the Prior Art In the art of collecting blood it is common practice to use an evacuated container having a pierceable and resealable closure closing off one end. When the venipuncture has been made, a pointed end of a cannula is pierced through the closure and blood flows into the unvented container. It is also common practice to use a syringe having a barrel with an attached needle and a plunger within the barrel. When the venipuncture has been made blood flows into the syringe barrel asthe plunger is withdrawn. The art is replete with disclosures of various types of valves for use with a cannula in a blood collecting assembly.

SUMMARY OF THE INVENTION The blood collecting assembly of the invention includes a cannula, a holder for the cannula, and an improved valve for the cannula. The valve is movable between a position in which the valve provides air venting through a restricted passage to provide a blood telltale and another position in which the valve prevents either air or blood from passing through the passage. The valve has means for facilitating its compression, and in particular its eccentric buckling relative to the cannula. This reduces the force which would otherwise be required to cause effective shortening of the length of the valve. The valve has a pierceable resealable wall or diaphragm through which the piercing end of the cannula can extend during the collection of blood and which can reseal when the valve returns to its extended position following the collection of blood. The valve preferably has a small internal diameter section and a large internal diameter section. The small internal diameter section is disposed at the open end of the cannula and the larger internal diameter section surrounds a substantial portion of the length of the interior marginal end of the cannula in one form of the invention. The small internal diameter section has an internal valve ring or seal around which air can pass in one position of the valve and which prevents the passage of both air and blood in the other position. The air vent can be provided in a number of ways such as by one or more holes in the valve body, by a groove in the hub which receives the valve, by a projection formed on the hub which receives the valve, or by a groove in the valve body at the hub.

The holder has a tubular body and a section, which has an internal conical surface, joining the tubular body. The tubular body providesa passageway into which an evacuated container having a pierceable closure is adapted to be inserted. The holder also has a visual indicator for indicating when the closure-piercing end has penetrated into the closure. The conical surface provides a stop for the container when the closurepiercing end has pierced through the closure.

In one embodiment of the invention the valve includes a pair of columns which can buckle to facilitate of the valve as the cannula is inserted through the pierceable closure of the blood collecting container and which can effect extention of valve immediately following removal of the cannula from the pierceable closure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partly broken away and partly in section, of a blood collecting assembly in accordance with one embodiment of the invention;

FIG. 2 is a side elevational view of an evacuated container with a closure closing off its one end, for use with the blood collecting assembly of the invention;

FIG. 3 is an enlarged sectional view of the embodiment shown in FIG. 1, with the container inserted into the passageway of the cannula holder and with its closure just touching the valve;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a fragmentary view similar to FIG. 3, but showing the valve in a position in which its air vent is closed off;

FIG. 6 is a sectional view similar to FIG. 5, but showing the valve eccentrically buckled and showing the cannula as penetrating the closure of the evacuated container;

FIG. 7 is a sectional view similar to FIG. 6, but showing the valve completely eccentrically buckled and showing the cannula as having penetrated through the closure;

FIG. 8 is a fragmentary sectional view of another embodiment of the invention.

FIG. 9 is an enlarged sectional view taken along line 99 of FIG. 8;

FIG. 10 is a fragmentary sectional view of yet another embodiment of the invention;

FIG. 11 is an enlarged sectional view taken along line 11-11 of FIG. 10;

FIG. 12 is a fragmentary sectional view of still another embodiment of the invention, showing the valve in its initial position;

FIG. 13 is a fragmentary sectional view of the embodiment shown in FIG. 12, but showing the valve in a position in which its air vent means is closed off;

FIG. 14 is an enlarged sectional view taken along line 1414 of FIG. 12;

FIG. 15 is a fragmentary sectional view of another embodiment of the invention, with the evacuated container inserted into the passageway of the cannula holder and with its closure just touching the valve;

FIG. 16 is a fragmentary view similar to FIG. 15, but showing the valve in a position in which its air vent valve is closed off;

FIG. 17 is a sectional view similar to FIG. 16, but showing the valve buckled outwardly and showing the cannula penetrating the closure of the container;

FIG. 18 is a sectional view similar to FIG. 17, but showing the valve completely buckled and showing the cannula as having penetrated through the closure;

FIG. 19 is a perspective view of the valve shown in section in FIGS. 15 through 18;

' FIG. 20 is a sectional view taken along line 20-20 of FIG. 19; and

FIG. 21 is a sectional view taken along line 21-21 of FIG. 20.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION Referring to FIGS. 1 and 3, there is shown a blood collecting assembly generally indicated at 20. The assembly includes a cannula 21 mounted in a onepiece holder 22. The holder 22 has a generally tubular body 23 with an end wall or end portion 24 at one end and terminating at an opening 25 at its other end. A hub portion or hub 27 formed integrally with the end wall 24 and having the same axis as the generally tubular body 23 extends into the interior of the passageway 23' provided by the body 23. A hub portion or hub 26 formed integrally with the end wall 24 and having the same axis as the hub 27 and the body 23 extends exteriorly of the passageway 23.

A sheath 28 removably received by the hub 26 preserves the sterility of the exterior marginal end 29 of the cannula 21 until the venipuncture is ready to be made. A valve 30 is disposed about the interior marginal end 31 of the cannula 21 and is shown to receive the hub 27. A removable cap 33 is shown in FIG. 1 to close off and preserve the sterility of the passageway 23', the valve 30, and the interior marginal end 31 of the cannula 21 until the assembly is ready to be used. The holder body 23 has a plurality of external annular rings 34 extending about its periphery. The rings 34 not only assist in gripping the holder 22, but they also strengthen the holder body 23.

The exterior marginal end 29 of the cannula 21 terminates at an open vein-piercing end 35. A bevel indicator 36 is formed on the periphery of the holder body in alignment with the bevel at the vein-piercing end 35. The interior marginal end 31 terminates at a closurepiercing end 37. It is preferred that the opening in the interior marginal end 31 be directly at the closurepiercing end 37 rather than in the side of the interior marginal end 31, although the invention does not require it to be located at the piercing end 37.

With reference to FIG. 2, there is shown a rigid evacuated container 38 in the form of a transparent glass tube. The container 38 has a pierceable, resealable elastomeric closure 39 closing off one end and maintaining the vacuum in the container 38.

With reference to FIGS. 3 and 4, the valve is shown to have a relatively small internal diameter section 40 joined to a relatively large diameter section 41. One marginal end 42 of the section 41 is slightly smaller than the remainder of the section 41 so that the marginal end 42 snugly embraces the hub 27.

The small internal diameter section 40 is shown to have an internal diameter which is only slightly larger than the outside diameter of the interior marginal end 31 of the cannula 21. An end wall or diaphram 43 closes off one end of the section 40. The valve 30 is composed of a pierceable, resealable, elastomeric material and thus the end 37 can pierce through the end wall 43 with which it is in alignment; when the end 37 is withdrawn the end wall 43 will reseal and thus the end wall 43 will be closed off again. More specifically, the valve 30 is composed of a styrene-butadiene copolymer although other suitable materials can be used. Formed integrally with the inside of the section 40 is an annular valve ring or seal 44. The inside diameter of the valve ring 44 is slightly less than the outside diameter of the interior marginal end 31 of the cannula 21. When the venipuncture is made, the valve 30 being in the initial position shown in FIG. 3, air in the cannula 21 can be vented through the open cannula end 37, through the restricted passage or space between the section and the outside of the interior marginal end 31; the air then passes through the space between the section 41 and the outside of the interior marginal end 31; from there the air can pass through air vent holes and 46 into the passageway 23 and from there to the atmosphere. In FIG. 3 the terminal end 47 of the section 41 is shown to be spaced from the interior surface of the end wall 24, and the tip of the end 37 is shown to be spaced a relatively long distance from the interior surface of the end wall 43 of the section 40. When the valve 30 is moved from the initial position shown in FIG. 3 by the closure 39 of the evacuated container 38, the terminal end 47 of the section 41 is moved into abutment with the end wall 24 of the holder 22 and the end wall 43 of the valve 30 is moved to a position relatively close to the tip of the end 37. In the position shown in FIG. 5, the valve ring 44 is in sealing engagement with outside of the interior marginal end 31. Accordingly, neither air nor blood can pass around the valve ring 44.

The holder 22 is preferably composed of a substantially rigid, transparent material. As the valve 30 is also sufficiently transparent, when the venipuncture is made, a blood telltale can be seen at the open end 37. The user can then move the evacuated container 38 further into the passageway 23 until the end 37 of the cannula 21 has pierced through the end wall 43 of the valve 30 and has penetrated into the closure 39, as shown in FIG. 6. In this position the open end 37 is sealed off by the closure 39. An indicator 48 in the form of an annular ring is formed integrally with the inside surface of the transparent holder body 23. As the container 38 is being moved from the position shown in FIG. 5 to the position shown in FIG. 6 by the user, the user can visually observe the position of the terminal end 49 of the closure 39 relatively to the indicator 48. When the terminal end 49 of the closure .is brought into alignment with the indicator 48, the end 37 is embedded in the closure 39 (FIG. 6). As the container 38 and its closure 39 are being moved from the position shown in FIG. 5 to the position shown in FIG. 6, the valve 30 buckles eccentrically with respect to the cannula interior marginal end 31. As shown in FIG. 6, this eccentric buckling takes place essentially only in the section 41. As the internal diameter of the valve section 41 is considerably greater than the external diameter of the interior marginal end 31 of the cannula 21, the cannula 21 does not essentially inhibit eccentric buckling of the section.

When the container 38 is moved still further into the passageway 23' from the position shown in FIG. 6 to the position shown in FIG. 7, the cannula opening at the end 37 communicates with the space within the evacuated container 38, thereby enabling flow of blood from the patient, through the cannula 21 and out of the open end 37 into the container 38. In this position, the valve 30 is buckled eccentrically to even a greater extent than shown in FIG. 6. In the position shown in FIG. 7, the end 49 of closure 39 is shown in abutment with a conical internal surface 18 of a conical section 19. The conical surface 18 serves as a stop when the container 38 is moved from the position shown in FIG. 6 to the position shown in FIG. 7. When the sample of blood has been collected, the container 38 is withdrawn from the passageway 23 and the valve 30 returns to the position shown in FIG. 5. It is preferred to coat the interior of the valve 30 with silicone or other suitable lubricants so that the marginal end 42 of the valve 30 can more easily slide on the hub 27 as the valve 30 is being shifted from the position shown in FIG. 3 to the position shown in FIG. 5 and so that the interior marginal end 31 will not impede either the compression, specifically the eccentric buckling, or the subsequent extension of the valve 30.

When the assembly'is to be used, the closure 33 is removed and the container 38 is inserted into the passageway23' of the holder 22 as shown in FIG. 3. Thereafter, the sheath 28 is removed and venipuncture is made. As soon-as the venipuncture is made, the user will see a small telltale of blood at the open end 37. The air that is in the cannula 21 is vented through the restricted passage, the section 41, the air holes 45 and 46, and the passageway 23 to the atmosphere. The restricted passage permits only a very low rate of blood flow but it is sufficient to provide the blood telltale. The space within the section 40 is made as small as practical so that the amount of blood that can pass into it when the valve 30 is in the position shown in FIG. 5 if very small. As soon as-the blood telltale appears, the container 38 is moved to the position shown in FIG. 5, thereby sealing off the opening at the end 37 from the atmosphere. The container 38 can now be moved to the position shown in FIG. 6. When the sample of blood is ready to be collected, the container 38 is moved to the position shown in FIG. 7, at which blood can pass through the open end 37 into the space within the container 38. When the sample of blood has been collected, the container 38 is removed from the passageway 23. As the cannula 21 leaves the closure 39, the

closure 39 automatically reseals to maintain the sterility of the blood collected in the container 38. The valve 30 automatically returns to the position shown in FIG. Sbecause of its resilience and the end wall 43 automatically reseals. In the position shown in FIG. 5, blood cannot flow past the valve ring 44 into the space between the section 41 and the interior marginal end 31. As soon as the blood sample has been collected, the marginal end 29 of the cannula 21 can be withdrawn from the. patients vein. However, should it be desired to take two or more samples, this can be done without making anothervenipuncture because the open end 35 of the cannula 21 can be left in the patients vein until all the samples have been collected. In particular, assuming a second sample is to be collected, a second container with its closure is inserted into the passageway 23' either to the position shown in FIG. 6 and from there to the position shown in FIG. 7, or directly to the position shown in FIG. 7. When the second samplehas been collected, the container and its closure are removed from the passageway 23 and valve 30 automatically returns to the position shown in FIG. 5. In like manner, additional samples can be collected.

In the embodiment of FIGS. 8 and 9, the same reference characters are used as in the embodiment of FIGS. 1 and 3 through 7, together with the letter a, to designate components having the same general construction, function and relative location. In' FIG. 8,

there are shown fragmentary portions of a cannula 21a' and a holder 220. A valve 30a differs from the valve 30 in that, instead of having air vent holes 45 and 46, marginal end 424 of the valve 30a has a groove 50. The

groove and hub 27a provide an air passage. The valve 30a is shown in FIG. 8 to be in a position corresponding to the initial position of the valve 30 in FIG. 3 in which there is communication with the atmosphere via groove 50. When the valve 30a is moved to a position corresponding to the position of the valve 30 in FIG. 5, an air sea] is provided by the hub 27a and the inside surface of the valve 30a beyond the groove 50.

In the embodiment of FIGS. 10 and 11, the same reference characters are used as in the embodiment of FIGS. 1 and 3 through 7, together with the letter b, to designate components having the same general construction, function and relative location. In FIG. 10 there are shown fragmentary portions of a cannula 21b and holder 22b. Valve 30b differs from the valve 30 in that it has no air vent holes 45 and 46. However, hub 27b has a projection or spacer 51. Marginal end 42b embraces the hub 27b, but a groove or air passage 52, 53 is provided at each side of the projection 51 between the marginal end 42b and the hub 27b. The valve 30b is shown in a position in which the air passages 52 and 53 provide communication with the atmosphere. When the valve 30b is moved to a position corresponding to the position of the valve 30 in FIG. 5, the terminal end 47b of the valve 30b is in sealing abutment with the inside surface of the end wall 24b, thereby preventing communication with the atmosphere.

In the embodiment of FIGS. 12, 13 and 14, the same reference characters are used as in the embodiment of FIGS. 1 and 3 through 7, together with the letter c, to designate components having the same general construction, function andrelative location. FIGS. 12and 14 depict fragmentary portions of cannula 21c and holder 22c, together with valve 30c. The valve 306 is shown in its initial position in FIG. 12 corresponding to the position of the valve 30 in FIG. 3, and the valve 300 is shown to be in different position in FIG. 13 corresponding to the position of the valve 30 in F IG. 5. The valve 30c does not have a valve ring or seal as does the valve 30. However, the hub 27c hasstep ped sections 54 and 55. The hub section 54 has a slightly smaller diameter than the hub section 55. In assembling the valve 300 onto the hub 27c it is brought up against shoulder 56 provided by the section 55. An internal groove 57 in' the hub 27c extends along the entire length of the hub section 54 and extends along part of the length of the hub section 55. When the valve 300 is in the position shown in FIG. 12, air can pass out of the open end 37c of the cannula 12c, through the space between small internal diameter section 400 and the interior marginal end 31c of the cannula 210 through the space between the large diameter section 410, through the air passage provided by the groove 57, and through passageway 23 to the atmosphere. When the valve 300 is moved from the position shown in FIG. 13 by moving the container 38 and its closure 39 further into the passageway 23c, marginal end 420 is moved into embracing and sealing relationship with the hub section beyond the groove 57, thereby closing off the groove 57.

In the embodiment of FIGS. 15 through 21, the same reference characters are used as in the embodiment of FIGS. 1 and 3 through 7, together with the letter d to designate components having the same general construction, function and relative location. In FIG. 15,

there are shown fragmentary portions of a cannula 21d 30d is shown to have a body with columns 60 and 61. The two columns 60 and 61 are shown to be diametrically opposite each other. Each column 60 and 61 is shown to be generally T-shaped in construction. The vertical bar part of each T-shaped column extends in a radial direction and the horizontal bar part of each T- shaped column extends in a directional perpendicular to the associated vertical bar part. The columns 60 and 61 are shown to be equally spaced apart. It is preferred to use two columns but it is within the spirit of the invention to use more than two columns, if desired. The columns are preferably identical in length, crosssectional area, shape and are symetrically located relative to the center line of the cannula 21d. This provides outward buckling as the valve 30d is moved from the position of FIG. 16 through the position of FIG. 17 to the position of FIG. 18. Accordingly buckling of columns 60 and 61 is completely free and unimpeded because there is no contact between the columns and the cannula 21 d during distention of the valve 30d. Likewise, resilient extension or straightening out of the columns 60 and 61, due to their construction and the nature of the material of which the valve 30d is composed, is also completely free and unimpeded because there is no contact between the columns and cannula 21d during extension of the valve 30d.

The one ends of the columns 60 and 61 are integrally joined by an annular collar or ring 62 which is slideably received by hub portion or hub 27d. The other ends of the columns are joined to a ring-shaped section 63 which is joined to a relatively small internal diameter section 40d. The buckling of the valve 30d takes place essentially entirely in the columns 60 and 61. When the columns 60 and 61 are completely buckled as shown in FIG. 18, the columns 60 and 61 are buckled in two different directions as is evident by a comparison to FIG. 17.

As in the embodiment of FIGS. 1 and 3 through 7, the section 40d is provided with an internal annular valve ring 44d for the same purpose. It is apparent that upon making the venipuncture, air can be vented to the atmosphere through the space between the cannula 31d and the side wall 65 above the valve ring 44d, through the space between columns 60 and 61, and through the space between the container 38 and the inside of the tubular body 23. The valve is closed off when in the position of FIG. 16. As in the other embodments, the valve 30d, and in particular the end of the section 40d is provided with an end wall 43d, in alignment with the cannula 21d, which is pierceable and resealable. As in the other embodiments the blood telltale is visible through the transparent holder 22d and the transparent valve 30d. The valve 30d is preferably composed of the same material as the other embodiments of the valve.

The embodiments of the blood collecting assembly shown in FIGS. 8 and 9, and 11, 12, 13 and 14, and through 21 are used in the same manner as the blood collecting assembly of the embodiment of FIGS. 1 and 3 through 7.

While it is evident that a valve as exemplified in the drawings in all the various embodiments is particularly useful when it is desired to make more than one venipuncture, the holder shown in the drawings can also be used without a valve. The holder is injection molded to the cannula; specifically, the holder has an end wall with an integral outwardly extending projection or hub and an inwardly extending projection or hub. The end wall and these hubs are injection molded about a substantial portion of the length of the cannula to provide solid holding of the cannula. The tapering section which joins the end wall and the tubular body makes an included angle of about 56 and is preferably between about 40 and This enables the venipuncture to be made at a more shallow angle of approach. This range of angles allows the exterior marginal end of the cannula to be relatively short, such as one inch, and this results in a cannula of shorter than usual length which affords the user greater control, and is less costly to manufacture in the first place. The relatively short exterior marginal end means that for a cannula of a given outside diameter and a given wall thickness, the exterior marginal end is more rigid. By way of example not limitation, the outside diameter of the holder body is about 0.80 inch, but it can be within a range of between about 0.550 inch and 0.850 inch. The wall thickness of the tubular body, the tapering section and the end wall are each about 0.05 inch, the outwardly extending hub is about0.35 inch in length, the inwardly extending hub is about 0.25 inch in length and the interior marginal end of the cannula is about 0.65 inch in length.

Various modifications of the foregoing embodiments will suggest themselves to those skilled in the art, and all such of these are within the scope of the invention which is best defined by the appended claims.

1. A holder, cannula and valve assembly for collecting blood, comprising: a holder having a generally tubular longitudinally extending passageway open atone end and having an end portion opposite the open end, a cannula extending longitudinally and connectedto the end portion of said holder, said cannula having an interior marginal end terminating in the passageway at a piercing end and having an exterior marginal end extending exteriorly of said holder and terminating ata vein-piercing end, said interior marginal end having an opening through which blood can pass, valve means received about said interior marginal end of said cannula and connected to said holder, said valve means including air vent means providing communication from said cannula opening, through said air vent means,'into said passageway, and to the atmosphere, and mounting means for said valve means connected to the end portion of said holder and enabling lengthwise shifting movement of the valve means relative to the cannula from a first position in which said cannula opening communicates with the atmosphere to provide a blood telltale at said cannula opening when said vein-piercing end has pierced the vein of a patient to a second'position at which said cannula opening is closed off from the atmosphere by said valve means to prevent additional blood from passing out of said cannula opening until blood is to be collected, said valve means being composed of a material which is cannula pierceable, resealable and sufficiently transparent to enable visual observation of the blood telltale through the valve means. v 2. An assembly as defined in claim 1, wherein the air vent means includes a groove which can provide communication with the atmosphere.

3. An assembly as defined in claim 1, said air vent means including an aperture in said valve means.

4. An assembly as defined in claim 1, said mounting means comprising a hub connected to said holder. said valve means being engaged with said hub, said air vent means including a groove in said hub.

5. An assembly as defined in claim 1, said mounting means comprising a hub connected to said holder, said valve means being engaged with said hub, said air vent means including a groove in said valve means where said valve means engages said hub.

6. An assembly as defined in claim 1, wherein said valve means includes a generally tubular body having a closed end and an integral sealing ring spaced apart from said closed end, said interior marginal end being out of sealing engagement with said sealing ring when said valve means is in its first position, said sealing ring said container. 

1. A holder, cannula and valve assembly for collecting blood, comprising: a holder having a generally tubular longitudinally extending passageway open at one end and having an end portion opposite the open end, a cannula extending longitudinally and connected to the end portion of said holder, said cannula having an interior marginal end terminating in the passAgeway at a piercing end and having an exterior marginal end extending exteriorly of said holder and terminating at a vein-piercing end, said interior marginal end having an opening through which blood can pass, valve means received about said interior marginal end of said cannula and connected to said holder, said valve means including air vent means providing communication from said cannula opening, through said air vent means, into said passageway, and to the atmosphere, and mounting means for said valve means connected to the end portion of said holder and enabling lengthwise shifting movement of the valve means relative to the cannula from a first position in which said cannula opening communicates with the atmosphere to provide a blood telltale at said cannula opening when said vein-piercing end has pierced the vein of a patient to a second position at which said cannula opening is closed off from the atmosphere by said valve means to prevent additional blood from passing out of said cannula opening until blood is to be collected, said valve means being composed of a material which is cannula pierceable, resealable and sufficiently transparent to enable visual observation of the blood telltale through the valve means.
 2. An assembly as defined in claim 1, wherein the air vent means includes a groove which can provide communication with the atmosphere.
 3. An assembly as defined in claim 1, said air vent means including an aperture in said valve means.
 4. An assembly as defined in claim 1, said mounting means comprising a hub connected to said holder, said valve means being engaged with said hub, said air vent means including a groove in said hub.
 5. An assembly as defined in claim 1, said mounting means comprising a hub connected to said holder, said valve means being engaged with said hub, said air vent means including a groove in said valve means where said valve means engages said hub.
 6. An assembly as defined in claim 1, wherein said valve means includes a generally tubular body having a closed end and an integral sealing ring spaced apart from said closed end, said interior marginal end being out of sealing engagement with said sealing ring when said valve means is in its first position, said sealing ring being in sealing engagement with the outer surface of said interior marginal end when said valve means is in its second position. 